Jet propulsion unit



Oct. 18, 1966 w, G. MCILWRAITH 3,279,180

JET PROPULSION UNIT Filed Deo. 22, 1964 5 Sheets-Sheet 1 FIG.v 1.

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06f- 13, 1956 w. G. MCILWRAITH JET PROPULSJON UNIT 5 Sheets-Sheet 2 Filed Dec.

i EMSCXM Oct. 18, 1966 w, G. MOILWRAITH 3,279,189

JET PRoPuLsIoN UNIT Filed Deo. 22, 1964 3 Sheets-Sheet 5 HG2, VIT* United States Patent O 3,279,180 .FET PRUIULSION UNIT William Gordon Mclllwraith, London, England, assigner to Shipelle Limited, London, England, a British company Filed Dec. 22, 1964, Ser. No. 420,361 Claims priority, application Great Britain, Aug. 27, 1964, 35,219/64 11 Claims. (Cl. Gil-222) This invention relates to jet propulsion units for boats.

It is an object of the present invention to provide a jet propulsion unit `for boats, which gives forward and reverse drive with steering and which provides a neutral drive.

According to the present invention there is provided a jet propulsion unit for boats, comprising a rotary impeller; a housing accommodating the rotary impeller and defining a fore-and-aft conduit formed with a front inlet ahead of said impeller, a rear end outlet and a base opening located between the rear end outlet and the impeller; a vane mounted on an upright pivotal axis at the rear of the housing to control iiuid flow through the rear end outlet and so effect steering; means to effect turning of said vane; a lateral flange formed at the base of one face of said vane to extend forwardly and cover said ibase opening when the vane is in a neutral-drive position across said conduit to close said rear end outlet, and a flap mounted at said opening to direct forwardly fluid flow from said opening when the vane is in a reverse-drive position across said conduit to close said rear end outlet and with said flange extending rearwardly to leave said base opening unobstructed.

Preferably, the flap is mounted, ibetween a pair of upright walls, on a transverse axis located towards the rear end of the flap which is weighted to act as a lever arm in urging the flap `upwardly during normal forward drive.

An embodiment of the invention will now be described, by way of example, with reference to the accompanying drawings in which:

FIGURES l and 1A are sectional side elevations showing a jet propulsion unit mounted on a boat, the section being on the line I I of FIG. 2;

FIG. 2 is a sectional rear elevation, on the line II-II of FIG. 1.

FIG. 3 is a fragmentary plan view, partly sectional on the line III-III of FIG. l.

Referring to the drawings, the jet propulsion unit is attached yby means of bolts to transom 11 of a boat, a wooden wedge 12 being provided as required to position the unit correctly. An inboard motor 13 is provided to power the unit.

The jet propulsion unit comprises a housing 14 which defines a fore-and-aft conduit 15. A rotary propeller 16 is arranged in the conduit which is formed with a front inlet 17, a rear end outlet 13 and a base opening 19 arranged ybetween the outlet 18 and the propeller. The propeller 16 is driven by the inboard motor 13, through shafts 20 and 21 which are joined by a flexible coupling 22, and is arranged to draw water through the inlet 17 for normal discharge through the rear outlet l8r.

A vane 23 is pivotally mounted on a central vertical spindle 24 and acts to control the direction of water flow through the rear outlet 18 and so effect steering of the boat in the forward direction.

A grooved pulley 25 is secured to the top of spindle 24 and turning of the vane is effected by means of a pair of cables 26 which lie in the pulley grooves and are anchored in the pulley by nipples 27. The cables 26 extend forwardly, encased in sheaths, to a steering wheel or tiller (not shown).

The vane 23 comprises a vane member 28 and a front Patented ct. 18, 1966 Mice plate 29 and a rear flared plate 30 are riveted to the member 28, rub-ber seal plates 31 being sandwiched `between the member 28 and plates 29 and 30. The member 2S is flared at its normally trailing end 32 and this, together with plate 3d, acts to urge the vane to the straight ahead position shown in the drawings.

The vane member 23 is formed at the base of one face with a lateral flange 33 of semicircular shape. During normal forward drive, as shown in FIG. 2, this horizontal flange 33, which has part of its periphery housed in one of a pair of side channels 34 of the housing 14, has little if any effect on the water flow. When the vane 23 is turned to lie across the conduit with the flange 33 extending forwardly, the flange closes the base opening 19 and as the vane closes also the rear outlet 18, no water ow takes place apart from possible leakage; thus a neutral drive is provided.

A flap 35 is pivotally mounted under the base opening 19 on a horizontal shaft 36 which extends transversely between a pair of rectangular Vertical walls 37. When the vane 23 is turned to lie across the conduit 15 with the ange 33 extending rearwardly, water flow is directed, by the vane, downwardly through the unobstructed base opening 19. The iiap then falls, to the position shown in broken lines in FIG. l, to act as a chute in directing the water flow forwardly, and thus a reverse drive is provided.

The side Walls of the conduit 15 are curved, at vertical edges 38, at the rear outlet 18 and terminate, at edges 39, just rearwardly of the spindle 24. Thus, during reverse drive if the vane 23 is turned through a small angle, water escapes laterally between the vane and a rear edge 39, to effect steering. Alternatively, the conduit walls may extend to or towards the trailing end of the housing 14 and be ported just rearwardly of the spindle 24 to provide a similar reverse-steering effect.

When the vane 23 returns to a forward-drive position, the flap, which is weighted at its rear end 410, pivots upwardly out of the path of the normal water stream and shields the base opening, as shown in full lines in FIG. 1. It is to be noted that the shape of the underside of the housing 14 produces an external water reaction which urges the flap upwardly towards its closingl position.

In a modication a chute, pivotally mounted at its rear end, is arranged under the base opening and a member extends as a lever arm from the chute to be engaged by fluid flow to or through the rear outlet to pivot the chute upwardly during normal forward drive. This movement may be facilitated by providing a plate at the forward edge of the base opening to derive a suction effect from the normal water flow which will act to draw the chute upwardly and hold the chute in that position.

The above constructions are primarily intended for application to small boats. The invention can, however, be adapted for other uses to control a jet stream of fluid, such as gas and liquid mixture or even gas itself.

I claim:

1. In a jet propulsion unit, a housing to receive a rotary impeller and defining a fore-and-aft conduit formed with a front inlet, a rear outlet and a base opening located between said impeller and said rear outlet, a pivotal vane mounted at the rear of the housing to control fluid flow through said rear outlet and so effect steering, means to effect turning of said vane, a lateral ange provided at the base of said vane to extend forwardly and cover said base opening when the vane is in a neutraldrive position across said conduit to close said rear outlet, and a flap mounted at said opening to direct forwardly uid How from said base opening when the vane is in a reverse drive position across said conduit to close said rear outlet and with said flange extending rearwardly.

2. A jet propulsion unit for boats, comprising a rotary impeller; a housing accommodating the rotary impeller and dening a fore-and-aft conduit formed with a front inlet ahead of said impeller, a rear end outlet and a base opening located between the re'ar end outlet and the impeller; a vane mounted on an upright pivotal axis at the rear of the housing to control fluid ow through the rear end outlet and so effect steering; means to eliect turning of said vane; a lateral ange formed at the base of one face of said vane to extend forwardly and cover said base opening when the vane is in a neutral-drive position across said conduit to close said rear end outlet, and a flap mounted at said opening to direct forwardly fluid ow from said opening when the vane is in a reverse-drive posi tion across said conduit to close said rear end outlet and with said flange extending rearwardly to leave said base opening unobstructed.

3. A jet propulsion unit according to claim 2, wherein a pair of upright fore-and-aft walls are mounted below said base opening and said tlap is pivotally mounted between said walls on a transverse axis located towards the rear part of the ap, said rear part being weighted to act as a lever arm in urging the ap upwardly during normal forward drive.

4. A jet propulsion unit according to claim 2, wherein said flange is of semicircular shape and channels are provided in said housing to accommodate the periphery of said ange.

5. A jet propulsion unit according to claim 2, wherein said housing includes upright walls which dene sides of said conduit adjacent said vane, said upright walls being curved to provide for sealing `contact with said vane and terminating just rearwardly of said vane axis to provide for steering during reverse drive.

6. A jet propulsion unit according to claim 2, wherein said housing includes upright walls which dene sides of l@ said conduit adjacent said vane, said upright walls being curved to provide for sealing contact with said vane and being ported just rearwardly of said vane axis to provide for steering during reverse drive.

7. A jet propulsion unit according to claim 2, wherein said vane is flared at its trailing end to urge the vane to a straight ahead position during forward drive.

8. A jet propulsion unit according to claim 5, wherein said vane comprises a plate-like vane member and at least one seal plate to promote close engagement with said curved upright walls.

9. A jet propulsion unit according to claim 2, wherein said vane comprises a plate-like vane member, a front plate, a rear plate and a pair of rubber vane seals sandwiched respectively between said plates and said vane member, said vane member and said rear plate being flared at their trailing ends to urge the vane to a straight-ahead position during forward drive` 10. A jet propulsion unit according to claim 2, wherein an upright spindle carried said vane, a grooved pulley is secured at the top of said spindle and forwardly extending cables are anchored in the grooves of said pulley for effecting turning of the vane.

11. A boat, a jet propulsion unit as claimed in claim 2 mounted on said boat, and an inboard motor mounted in said boat to drive said impeller.

MARK NEWMAN, Primary Examiner. C. R. CROYLE, Assistant Examiner. 

1. IN A JET PROPULSION UNIT, A HOUSING TO RECEIVE A ROTARY IMPELLER AND DEFINING A FORE-AND-AFT CONDUIT FORMED WITH A FRONT INLET, A REAR OUTLET AND A BASE OPENING LOCATED BETWEEN SAID IMPELLER AND SAID REAR OUTLET, A PIVOTAL VANE MOUNTED AT THE REAR OF THE HOUSING TO CONTROL FLUID FLOW THROUGH SAID REAR OUTLET AND SO EFFECT STEERING, MEANS TO EFFECT TURNING OF SAID VANE, A LATERAL FLANGE PROVIDED AT THE BASE OF SAID VANE TO EXTEND FORWARDLY AND COVER SAID BASE OPENING WHEN THE VANE IS IN A NEUTRALDRIVE POSITION ACROSS SAID CONDUIT TO CLOSE SAID REAR OUTLET, AND A FLAP MOUNTED AT SAID OPENING TO DIRECT FORWARDLY FLUID FLOW FROM SAID BASE OPENING WHEN THE VANE IS IN A REVERSE DRIVE POSITION ACROSS SAID CONDUIT TO CLOSE SAID REAR OUTLET AND WITH SAID FLANGE EXTENDING REARWARDLY. 